With a two-pipe air-conditioning system in the related art, the operation modes of the indoor units include a refrigerating mode (namely, all of the indoor units work in the refrigerating mode) and a heating mode (namely, all of the indoor units work in the heating mode). With a three-pipe air-conditioning system in the related art, the operation modes of the indoor units include a refrigerating mode, a heating mode and a mixed mode (namely, a part of the indoor units may work in the heating mode and the other part of the indoor units may work in the refrigerating mode simultaneously).
In the related art, the outdoor units used in the two-pipe air-conditioning system or the three-pipe air-conditioning system respectively have different structures, and cannot be interchangeable, i.e. the outdoor unit used in the two-pipe air-conditioning system cannot be adopted in the three-pipe air-conditioning system, on the contrary, the outdoor unit used in the three-pipe air-conditioning system cannot be adopted in the two-pipe air-conditioning system either.
In order to meet assembling requirements of the two-pipe air-conditioning system and the three-pipe air-conditioning system, manufacturers shall manufacture two types of outdoor units having different structures, prepare different production lines and equipment for the two types of outdoor units, and design different production planning, thus increasing the manufacturing cost of the air-conditioner and affecting subsequent maintenance.